A variety of evidence from clinical and neurosurgical sources indicates that the human brain is laterally specialized for cognition. This evidence has been confirmed in studies of normal subjects. The left hemisphere is predominantly involved in verbal and other analytic functions, the right in spatial and other holistic processing. In the past three years we have developed and refined an electrophysiological method for studying this lateral specialization in normal people. By studying EEG asymmetry we are able to distinguish these two cognitive modes as they occur in normal subjects using simple scalp recording. In brief, we examined the EEGs of subjects performing verbal and spatial tasks to determine whether there were differences in the activity between the appropriate and inappropriate hemispheres. We found that the ratio of alpha power right/left is significantly higher in verbal and arithmetic tasks than in spatial tasks; the beta and theta bands show a less consistent effect. The delta band shows no such systematic effect of cognitive mode. Now that we have established a method for determining lateralization of cognitive function in normal subjects, we propose to study several major areas of concern; the generality of lateral specialization in the population, including left handed and ambidexterous people, the role of lateral specialization in critical academic skills, the effect of social drugs on hemispheric interaction, and the possibility of training voluntary control over patterns of lateral asymmetry using EEG biofeedback.